1. Field of the Invention
This invention relates to a cassette inspecting system, and more particularly to a cassette inspecting system for inspecting the function of a lid which is spring-urged toward the closed position in a cassette such as a video cassette.
2. Description of the Prior Art
For example, a VHS video cassette is provided with a lid called a guard panel which is movable between an open position and a closed position and is spring-urged toward the closed position.
When manufacturing such a video cassette, it is necessary to inspect whether the lid can be correctly opened and closed, and more particularly whether the urging force of the lid spring which urges the lid toward the closed position is in a predetermined range. Such inspection may be effected by forcing the lid toward the open position by a pushing member which is provided with a predetermined urging force by a spring and by detecting the urging force of the lid spring through the displacement of the spring which urges the pushing member.
However, depending on the kind of the cassette the difference between the upper limit and the lower limit of the urging force of the lid spring is very large, e.g., the upper limit is 100 g and the lower limit is 10 g, and accordingly, when the inspection is effected by the pushing member which is urged by a single spring, the detecting error will be too large. On the other hand, when the upper and lower limits are detected by different pushing members, the inspecting system will be complicated and the inspecting cost will be increased.